U.S. patent number 10,272,995 [Application Number 15/145,342] was granted by the patent office on 2019-04-30 for electrically powered personal vehicle and flight control method.
This patent grant is currently assigned to SkyKar Inc.. The grantee listed for this patent is SkyKar Inc.. Invention is credited to Markus Leng.
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United States Patent |
10,272,995 |
Leng |
April 30, 2019 |
Electrically powered personal vehicle and flight control method
Abstract
An aerial vehicle includes at least one wing, a plurality of
thrust producing elements on the at least one wing, a plurality of
electric motors equal to the number of thrust producing elements
for individually driving each of the thrust producing elements, at
least one battery for providing power to the motors, and a flight
control system to control the operation of the vehicle. The aerial
vehicle may include a fuselage configuration to facilitate takeoffs
and landings in horizontal, vertical and transient orientations,
redundant control and thrust elements to improve reliability and
means of controlling the orientation stability of the vehicle in
low power and multiple loss of propulsion system situations. Method
of flying an aerial vehicle includes the variation of the
rotational speed of the thrust producing elements to achieve active
vehicle control.
Inventors: |
Leng; Markus (Warkworth,
CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
SkyKar Inc. |
Etobicoke |
N/A |
CA |
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Assignee: |
SkyKar Inc. (Etobicoke, ON,
CA)
|
Family
ID: |
50431976 |
Appl.
No.: |
15/145,342 |
Filed: |
May 3, 2016 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20160244156 A1 |
Aug 25, 2016 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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14046729 |
Oct 4, 2013 |
9346542 |
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61710216 |
Oct 5, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B64C
27/26 (20130101); B64C 11/46 (20130101); B64D
31/12 (20130101); B60L 58/12 (20190201); B64D
17/00 (20130101); B60L 50/52 (20190201); B64C
1/26 (20130101); B64D 27/24 (20130101); B64D
33/08 (20130101); B64C 29/0025 (20130101); B64C
29/00 (20130101); B64C 29/02 (20130101); B64C
15/02 (20130101); Y02T 10/70 (20130101); B64C
39/026 (20130101) |
Current International
Class: |
B64C
27/26 (20060101); B64C 11/46 (20060101); B64C
15/02 (20060101); B64D 17/00 (20060101); B64D
27/24 (20060101); B64D 31/12 (20060101); B64D
33/08 (20060101); B64C 29/02 (20060101); B64C
1/26 (20060101); B64C 29/00 (20060101); B64C
39/02 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Ellis; Christopher P
Attorney, Agent or Firm: Derenyi; Eugene F. Fogler, Rubinoff
LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of U.S. application Ser. No.
14/046,729 filed Oct. 4, 2013, which is pending as of the time of
filing, which claims the benefit of priority from U.S. Provisional
Application Ser. No. 61/710,216 filed Oct. 5, 2012 which is
incorporated herein by reference.
Claims
I claim:
1. An aerial vehicle comprising: one or more wings, three or more
thrust producing elements mounted in a fixed non-articulating
relationship to the one or more wings, a plurality of electric
motors for driving the thrust producing elements, at least one of
the electric motors comprising a stationary electromagnetic stator,
a rotor having a rotational axis, wherein the rotor comprises a
cylindrically shaped structure comprising a plurality of concentric
layers, and, a plurality of permanent magnets disposed on the
cylindrical shaped structure, at least one battery for providing
power to the motors, and a flight control system having a motor
controller for controlling the rotational speed and direction of
rotation of each thrust producing element.
2. The aerial vehicle according to claim 1, further comprising: a
fuselage located on a central longitudinal axis of the vehicle,
wherein the one or more wings comprising two wings extending
perpendicular to the central longitudinal axis, wherein the wings
are stacked, and wherein the wings are spaced from each other along
the central longitudinal axis.
3. The aerial vehicle according to claim 2 wherein the vehicle
further comprises a bottom having a first facet at a first angle
and a second facet at a second angle, whereby the vehicle rests at
a first orientation when resting on the first facet and rests at a
second orientation when the vehicle rests on the second facet.
4. The aerial vehicle according to claim 3 wherein the first
orientation is conducive to a vertical or near vertical take-off
and the second orientation is conducive to a horizontal or near
horizontal take-off.
5. The aerial vehicle according to claim 1, wherein the number of
thrust producing elements is selected from the group consisting of
3, 4, 6, 8, 10 and 12.
6. The aerial vehicle according to claim 1, wherein the thrust
producing elements are selected from the group consisting of
propellers, turbines and ducted fans.
7. The aerial vehicle according to claim 1, wherein the vehicle is
tailless, and the control system is adapted vary the amount of
rotational energy absorbed by individual motors when the individual
motors are operated in a generator mode and are driven by rotation
of the thrust producing elements connected to the individual
motors, thereby effecting control of the orientation of the vehicle
without the use of control surfaces.
8. The aerial vehicle according to claim 1, wherein the number of
thrust producing elements is at least eight, the thrust producing
elements are grouped into four quadrants with at least two thrust
producing elements located in each quadrant, the control system is
adapted to reverse the rotation of a first thrust control element
in a first quadrant, vary the rotation of a second thrust control
element in the first quadrant, when all thrust control elements are
not operating in a quadrant opposite the first quadrant, thereby
effecting control of the orientation of the vehicle.
9. The aerial vehicle according to claim 1, wherein one or more of
the thrust producing elements are adapted for hover and one or more
of the thrust producing elements are adapted for forward
flight.
10. The aerial vehicle according to claim 1, further comprising: a
battery energy level monitor for determining the energy level in
the battery configured to take a first measurement of the voltage
in the battery at an initial epoch under a substantially no-load
condition, relate the voltage measurement to a value of potential
energy stored in the battery at the initial epoch, take a second
measurement of voltage in the battery and a measurement of current
flow into or out of the battery at a subsequent epoch, integrate
the second measurement of voltage and the current flow measurement
with respect to time, determine an energy change from the
integration, relate the energy change to the initial energy level
to calculate the energy level of the battery at the subsequent
epoch.
11. The aerial vehicle according to claim 1, wherein in horizontal
or near horizontal flight, the control system is adapted to
increase rotational speed of some of the thrust producing elements
to make a yaw turn whereby the vehicle turns substantially around
the yaw axis but does not turn substantially around the pitch or
roll axis.
12. A method of operating an aerial vehicle comprising one or more
wings, three or more thrust producing elements mounted in a fixed
non-articulating relationship to the one or more wings, and a
plurality of electric motors for driving the thrust producing
elements, comprising: differentially varying the thrust of the
thrust producing elements thereby altering the orientation of the
vehicle least one of the electric motors comprising a stationary
electromagnetic stator, a rotor having a rotational axis, wherein
the rotor comprises a cylindrically shaped structure comprising a
plurality of concentric layers, and, a plurality of permanent
magnets disposed on the cylindrical shaped structure.
13. The method according to claim 12 wherein the number of thrust
producing elements is selected from the group consisting of 3, 4,
6, 8, 10 and 12.
14. The aerial vehicle according to claim 12, wherein the thrust
producing elements are selected from the group consisting of
propellers, turbines and ducted fans.
15. The method according to claim 12, further comprising:
differentially varying the amount of rotational energy absorbed by
the individual motors when the individual motors are operated in a
generator mode and are driven by rotation of the thrust producing
elements connected to the individual motors, thereby effecting
control of the orientation of the vehicle without the use of
control surfaces.
16. The method according to claim 12, wherein the number of thrust
producing elements is at least eight and the thrust producing
elements are grouped into four quadrants with at least two thrust
producing elements located in each quadrant, further comprising:
reversing the rotation of a first thrust control element in a first
quadrant, varying the rotation of a second thrust control element
in the first quadrant, when all thrust control elements are not
operating in a quadrant opposite the first quadrant, thereby
effecting control of the orientation of the vehicle.
17. The method according to claim 12, wherein one or more of the
thrust producing elements are adapted for hover and one or more of
the thrust producing elements are adapted for forward flight.
18. The method according to claim 12 further comprising: providing
a battery for providing power to the motors, monitoring the energy
level in the battery comprising: taking a first measurement of the
voltage in the battery at an initial epoch under a substantially
no-load condition, relating the voltage measurement to a value of
potential energy stored in the battery at the initial epoch, taking
a second measurement of voltage in the battery and a measurement of
current flow into or out of the battery at a subsequent epoch,
integrating the second measurement of voltage and the current flow
measurement with respect to time, determining an energy change from
the integration, and relating the energy change to the initial
energy level to calculate the energy level of the battery at the
subsequent epoch.
19. The method according to claim 12 further comprising increasing
rotational speed of some of the thrust producing elements to yaw
the vehicle thereby inducing the vehicle to roll resulting in a
coordinated turn.
Description
TECHNICAL FIELD
This invention relates to the field of aerial vehicles in general
and the field of electrically powered aerial vehicles and a flight
control methods in particular.
BACKGROUND
Electrically powered aerial vehicles and in particular vertical
takeoff and landing (VTOL) vehicles have helicopter type
configurations or wing type configurations in which the engines
must articulate (either on their own or with rotatable wings) for
vertical and horizontal translational flight. Such vehicles are
complicated.
SUMMARY
According to one aspect of the present invention there is provided
an aerial vehicle including a cockpit located on a central
longitudinal axis of the vehicle, a fixed, elongated rectilinear
wing spaced apart from each end of the cockpit and extending
perpendicular to the central longitudinal axis, struts connecting
the ends of the wings to the cockpit and to each other, a plurality
of propellers on a leading edge of each wing, the propellers having
rotational axis such that the wash from the propellers is directed
along the surfaces of the wing to provide lift and forward thrust
to the vehicle, a plurality of electric motors for driving the
propellers, at least one battery for providing power to the motors,
and a flight control system having a separate motor controller for
each motor to control the rotational speed of each propeller.
According to another aspect of the present invention there is
provided an aerial vehicle including a fuselage located on a
central longitudinal axis of the vehicle, an elongated rectilinear
wing extending perpendicular to the central longitudinal axis and
fixed to each end of the fuselage, a plurality of propellers on a
leading edge of each wing, the propellers having rotational axis
such that the wash from the propellers is directed along at least
one surface of the wing to provide lift and forward thrust to the
vehicle, a plurality of electric motors for driving the propellers,
at least one battery for providing power to the motors, and a
flight control system having a separate motor controller for each
motor to control the rotational speed of each propeller.
According to a further aspect of the present invention, there is
provided a method of flying an aerial vehicle including a cockpit,
upper and lower wings attached to the cockpit and a plurality of
propellers on each wing, the steps including increasing or
decreasing the rotational speed of propellers on one wing relative
the rotational speed of propellers on the other wing whereby the
orientation of the vehicle relative to the pitch axis can be
varied.
According to a still further aspect of the present invention, there
is provided a method of flying an aerial vehicle including a
fuselage, first and second wings attached to the fuselage and a
plurality of propellers on each wing, the steps including
increasing or decreasing the rotational speed of propellers on one
wing relative to the rotational speed of propellers on the other
wing whereby the orientation of the vehicle relative to the pitch
axis can be varied.
According to a still further aspect of the present invention, one
or more of the propellers are sized and configured for a first
speed or condition, such as hover, while one or more other
propellers are optimized for one or more other speeds, such as, for
horizontal flight. For example, in an eight propeller
configuration, four propellers can be optimized for hover flight in
terms of one or more of the pitch, diameter, foil design and number
of blades while four additional propellers can be optimized for
forward flight, again in terms of one or more of the pitch,
diameter, foil design and number of blades. In certain other
aspects, one or more of the pitch, diameter, foil design and number
of blades of one or more of the propellers may be varied to adapt
the propellers for one or more other desired performance
characteristic.
According to a further aspect of the present invention, there is
provided a method of flying an aerial vehicle including a cockpit,
upper and lower wings staggered vertically and longitudinally
relative to each other and a plurality of propellers on each wing,
the steps including increasing or decreasing the rotational speed
of propellers on one wing relative the rotational speed of
propellers on the other wing whereby the orientation of the vehicle
relative to the pitch axis can be varied.
According to a still further aspect of the present invention, there
is provided an active control system for control of an aerial
vehicle with a plurality of thrust producing elements of eight or
more wherein the thrust producing elements are grouped into logical
and physical quadrants comprising of two or more thrust producing
elements each. The control system allows for the control of the
thrust producing elements in the event of failure of all propulsion
systems in the same quadrant by allowing some of the thrust
producing elements in the opposite quadrant to produce negative
thrust. This method allows for all thrust producing elements, other
than the elements operating in reverse, to operate in a range
allowing for controllability.
According to a still further aspect of the present invention, there
is provided an aerial vehicle including one or more wings, three or
more thrust producing elements mounted in a fixed non-articulating
relationship to the one or more wings, a plurality of electric
motors for driving the thrust producing elements, at least one
battery for providing power to the motors, and a flight control
system having a motor controller for controlling the rotational
speed and direction of rotation of each thrust producing
element.
In certain embodiments, the vehicle may further include a fuselage
located on a central longitudinal axis of the vehicle, wherein the
one or more wings comprising two wings extending perpendicular to
the central longitudinal axis, the wings are stacked and spaced
from each other along the central longitudinal axis and along an
axis perpendicular to the central longitudinal axis.
In certain embodiments, the vehicle may further include a bottom
having a first facet at a first angle and a second facet at a
second angle, whereby the vehicle rests at a first orientation when
resting on the first facet and rests at a second orientation when
the vehicle rests on the second facet, wherein the first
orientation may be conducive to a vertical or near vertical
take-off and the second orientation may be conducive to a
horizontal or near horizontal take-off.
In certain embodiments, the aerial vehicle is tailless, and the
control system is adapted vary the amount of rotational energy
absorbed by individual motors when the individual motors are
operated in a generator mode and are driven by rotation of the
thrust producing elements connected to the individual motors,
thereby effecting control of the orientation of the vehicle without
the use of control surfaces.
In certain embodiments, the number of thrust producing elements is
at least eight, the thrust producing elements are grouped into four
quadrants with at least two thrust producing elements located in
each quadrant, the control system is adapted to reverse the
rotation of a first thrust control element in a first quadrant,
vary the rotation of a second thrust control element in the first
quadrant, when all thrust control elements are not operating in a
quadrant opposite the first quadrant, thereby effecting control of
the orientation of the vehicle.
In certain embodiments, one or more of the thrust producing
elements are adapted for hover and one or more of the thrust
producing elements are adapted for forward flight.
In certain embodiments, the vehicle further includes a battery
energy level monitor for determining the energy level in the
battery configured to take a first measurement of the voltage in
the battery at an initial epoch under a substantially no-load
condition, relate the voltage measurement to a value of potential
energy stored in the battery at the initial epoch, take a second
measurement of voltage in the battery and a measurement of current
flow into or out of the battery at a subsequent epoch, integrate
the second measurement of voltage and the current flow measurement
with respect to time, determine an energy change from the
integration, and relate the energy change to the initial energy
level to calculate the energy level of the battery at the
subsequent epoch.
In certain embodiments, the aerial vehicle in horizontal or near
horizontal flight, the control system is adapted to increase
rotation of some of the thrust producing elements to make a yaw
turn whereby the vehicle turns substantially around the yaw axis
but does not turn substantially around the pitch or roll axis.
According to a still further aspect of the present invention, there
is provided a method of operating an aerial vehicle comprising one
or more wings, three or more thrust producing elements mounted in a
fixed non-articulating relationship to the one or more wings, and a
plurality of electric motors for driving the thrust producing
elements, including differentially varying the thrust of the thrust
producing elements thereby altering the orientation of the
vehicle.
In certain embodiments, the method further includes differentially
varying the amount of rotational energy absorbed by the individual
motors when the individual motors are operated in a generator mode
and are driven by rotation of the thrust producing elements
connected to the individual motors, thereby effecting control of
the orientation of the vehicle without the use of control
surfaces.
In certain embodiments, the number of thrust producing elements is
at least eight and the thrust producing elements are grouped into
four quadrants with at least two thrust producing elements located
in each quadrant, and the method further includes reversing the
rotational direction of a first thrust control element in a first
quadrant, varying the rotational speed of a second thrust control
element in the first quadrant, when all thrust control elements are
not operating in a quadrant opposite the first quadrant, thereby
effecting control of the orientation of the vehicle.
In certain embodiments, the method further includes providing a
battery for providing power to the motors, monitoring the energy
level in the battery including taking a first measurement of the
voltage in the battery at an initial epoch under a substantially
no-load condition, relating the voltage measurement to a value of
potential energy stored in the battery at the initial epoch, taking
a second measurement of voltage in the battery and a measurement of
current flow into or out of the battery at a subsequent epoch,
integrating the second measurement of voltage and the current flow
measurement with respect to time, determining an energy change from
the integration, and relating the energy change to the initial
energy level to calculate the energy level of the battery at the
subsequent epoch.
In certain embodiments, the method further includes increasing the
rotational speed of some of the thrust producing elements to yaw
the vehicle thereby inducing the vehicle to roll.
DRAWINGS
The invention is described below in greater detail with reference
to the accompanying drawings which illustrate preferred embodiments
of the invention, and wherein:
FIG. 1 is a perspective view of an aerial vehicle according to an
embodiment of the present invention;
FIG. 2 is a bottom view of the vehicle of FIG. 1;
FIG. 3 is an isometric view of an aerial vehicle according to
another embodiment of the present invention;
FIG. 4 is a top view of the vehicle of FIG. 3;
FIG. 5 is a bottom view of the vehicle of FIGS. 3 and 4;
FIG. 6 is an electrical schematic of a flight control system usable
in the vehicles of FIGS. 1 to 5;
FIG. 7 is an electrical schematic of an alternate flight control
system usable in the vehicles of FIGS. 1 to 5;
FIG. 8 is an electrical schematic of an alternate flight control
system usable in the vehicles of FIGS. 1 to 5; and,
FIG. 9 is an end view of a motor with flux rings according to an
embodiment of the present invention.
DETAILED DESCRIPTION
Referring to FIGS. 1 and 2 of the drawings, one embodiment of the
aerial vehicle of the present invention includes a cockpit
indicated generally at 1 for accommodating an operator 2. Wings 3
and 4 are spaced apart from the front and rear of the cockpit 1.
The wings 3 and 4 are perpendicular to the central longitudinal
axis of the vehicle. A first pair of outer struts 5 extend between
the wings 3 and 4 on each side of the cockpit 1. The outer struts 5
are connected to the wings 3 and 4 proximate their outer ends. The
struts 5 are also connected to the centers of the sides of the
cockpit 1.
The sides of the cockpit 1 are defined by inner struts 7, which
define a diamond shaped structure extending between the centers of
the wings 3 and 4. The cockpit 1 is basically a backrest 8 and a
floor 9 (FIG. 2) extending between the struts 7. The struts 5 are
connected to the inner struts 7 and thus to the cockpit at the
longitudinal center of the vehicle. The struts 5 and 7 are
connected to the wings 3 and 4 by barrel hinges (not shown), which
include removable pivot pins. Of course, the struts can be
permanently connected to the wings 3 and 4. By the same token, the
cockpit 1 can separate from and permanently connected to the struts
5 and 7 or removable for disassembly of the vehicle for
transporting it in pieces. In other embodiments, a fuselage may be
provided. In further embodiments, the vehicle may have more than
two wings, for example three wings, and motors may be provided on
more than two wings.
Each of the elongated, rectilinear wings 3 and 4 includes an inner
box or frame (not shown) formed of a rigid foam such as
Styrofoam.RTM. covered by a layer of epoxy-carbon composite. The
box contains four electric batteries 13 (FIG. 6) for providing
energy to a like number of DC electric motors 14. In other
embodiments, the wings 3 and 4 may be of different construction and
the electric batteries may be housed elsewhere in the vehicle.
The motors 14 are electronically commutated motors, and preferable
outrunner brushless DC motors. The motors 14 may be air cooled
using a vacuum disc (not shown) for evacuating air from the motors
and in turn drawing air into the motors 14 preferably from the back
of the motors. The vacuum discs are driven by the motors 14 and
help cool the motors 14 especially when air is not flowing to the
motors 14 when the vehicle is stationary, such as when the vehicle
is on the ground or hovering. The motors 14 also include flux rings
35 defined by steel rings with super magnets 40 spaced around the
inner circumferences of the steel rings 38 and stators 4 inside the
rings 38. In one embodiment of the present invention, the flux
rings 35 are formed using cylindrical laminated steel sections,
preferably concentric layers of electronic steel bonded together
with structural epoxy. The flux ring structure of the rotor of the
motor 14 is optional. In certain embodiments, a conventional solid
rotor ring may be used. The preferred motors are capable of
approximately 20 peak horsepower for about 2 minutes. The batteries
are preferably lithium polymer batteries but other suitable
batteries may be used'. An on-board battery charger (not shown)
receives power from a standard household 110 volt outlet. In other
embodiments, other types of electrically powered motors may be
used. For example, motors of other suitable power and speed
capacities and types (such as but not limited to inrunner brushless
DC motors), may be used.
The motors 14 are mounted on the top, leading edge 15 of each wing
3 and 4 for driving four propellers 16. The motors 14 are oriented
on the wings 3 and 4 such that the plane defined by the rotation of
each propeller 16 is preferably inclined by 6.degree. with respect
to a central longitudinal plane of the wing to which they are
attached such that the propellers 16 are orthogonal to the
direction of flight of the vehicle when the vehicle is in
horizontal flight. However, the angle of inclination of the plane
of the propellers may vary in other embodiments depending upon the
optimum characteristic of the vehicle, such as for but not limited
to speed, load and angle of attack. For example, the angle of
inclination may be as small as 0.degree., may a negative angle, or
may be 3.degree. for higher speed applications, or greater than the
preferred 6.degree.. In other embodiments, the inclination of the
propellers on one wing may differ from the inclination of the
propellers on the other wing. In certain embodiments, the
propellers need not all have the same pitch angle. For example,
when eight propellers are used, a first set of four propellers may
have a certain forward pitch for high speed travel and a second set
of four propellers may have a shallower pitch, relative to the
forward pitch of the first set of four propellers, for hover. In
other embodiments, the diameter of the propellers may vary. For
example, smaller propellers may be selected for improved hover
control. Other combinations of pitch, diameter, foil design and
number of blades may be used according to the operational needs of
the vehicle.
While each wing 3 and 4 is provided with four propellers 16, it
will be appreciated that two, six, eight or more than eight
propellers could be provided on each wing. Certain propellers
rotated in one direction as indicated by the arrows A in FIG. 1 and
all of the remaining propellers rotated in the opposite direction
as indicate by arrows B in FIG. 1. The direction of rotation of
each propeller may vary in other embodiments.
The aerial vehicle of FIGS. 3 to 5 is similar to the vehicle of
FIGS. 1 and 2 except that the cockpit 1 is part of a fuselage 20
extending between the centers of the front and rear wings 3 and 4
respectively. The fuselage 20 includes struts 5 (FIG. 3) and a skin
covering the struts and a frame (not shown) behind the seat back 8.
The cockpit 1 is covered by a domed canopy 21, and the bottom 22 of
the fuselage 20 is multi-faceted. The bottom 22 includes a first
bottom surface 47 at a first angle, a second bottom surface 48 at a
second angle and a third bottom surface 49 at a third angle. This
permits the vehicle when on the ground to site at three angles of
repose. In certain embodiments, the vehicle may sit on bottom
surface 47 at a first angle of repose or on bottom surface 48 at a
second angle of repose or on bottom surface 49 at a third angle of
repose. In certain embodiments, the surface on which to sit the
vehicle may be chosen for example to facilitate take-off. For
example, for a near horizontal take-off orientation, the vehicle
may sit on the bottom surface 47. For a near vertical take-off
orientation, the vehicle may sit on the bottom surface 49. It is
understood that the bottom 22 is not limited to three bottom
surfaces or to the angles depicted in FIG. 3. In certain
embodiments, the bottom 22 may in whole or in part be curved or
arcuate as opposed to multi-facetted. In certain other embodiments,
the fuselage may not include struts or a canopy and the fuselage
may be smooth or curved instead of multi-faceted.
Referring to FIG. 6, the operation of the aerial vehicle is
controlled by a flight control system, which includes a motor
controller 24 connecting each motor 14 to a battery 13. In FIG. 6,
to facilitate an understanding of the control system, the motors 14
rotating in the direction of arrows A (FIG. 1) are labeled A1-A4,
motors A1-A2 being on one wing 4 and motors A3-A4 being mounted on
the other wing 3, and motors 14 rotating in the direction of arrows
B are labeled B1-B4, motors B1-B2 being mounted on wing 4 and
motors B3-B4 being mounted on wing 3. The batteries 13 and motor
controllers 24 connected to the motors A2-A4 and B1-B4 are also
labeled A1-A4 and B1-B4, respectively. The batteries 13 are in turn
connected to three power supply type "OR" gates 25. A separate
back-up battery 26 is connected to the "OR" gates 25 for providing
emergency power in the event that the batteries 13 become
sufficiently discharged that they can no longer operate the motors
14. Each "OR" gate 25 is connected to a flight processor 17, which
is connected to a sensor package 28 for measuring one or more of
the vehicle's velocity, orientation and acceleration.--Each sensor
package preferably includes three solid state gyroscopes (not
shown) for measuring rotational acceleration--in three
orientations, three accelerometers (not shown) for measuring
acceleration in three orientations, a magnetometer (not shown) for
measuring magnetic field strength in three orientations, a
barometric pressure sensor (not shown) and a GPS device (not
shown). It will be appreciated that more or fewer sensor packages,
more or fewer sensors per sensor package and fight processors can
be used. However, it is preferred and advisable to have redundant
controls in the vehicle. The flight processors 27 take input from
the sensor packages 28 and using software running on each flight
processor 27, each flight processor 27 acts as a virtual inertial
measuring unit ("Virtual IMU") (not shown) and calculates vectors
for a point on the aerial vehicle representing the centre of
gravity. The vectors calculated include a position vector, an
orientation vector, a velocity vector and an acceleration vector.
These vectors can be calculated for points on the aerial vehicle
other than the centre of gravity. Not all of the vectors need to be
calculated, or not each time.
The flight processors 27 also provide data to a tablet computer 29
which acts as a display for the user 2. A different type of display
may be used or omitted altogether. The GPS device is used to
correct the Virtual IMU in accelerated frames of reference. The GPS
device is optional.
Each flight processor 27 is also connected to a joystick 31 and a
throttle stick 32 both of which are controlled by the operator 2 of
the vehicle. A cellular network data link 33 and/or a WiFi data
link 34 can be connected to the computer 29.
In operation, each processor 27 receives data from each sensor
package 28 and uses a polling method to average out the sensor
information and calculate the Virtual IMU which preferably is
calculated at the center of gravity of the vehicle to calculate the
orientation and altitude of the vehicle. The polled data is used by
each processor to adjust the rotational speed of the propellers by
sending the appropriate commands to the motor controllers. The
motor controllers receive data from each of the processors 27 and
use polling to determine which data to use in controlling the
motors 14. The control system is adapted to provide thrust vector
redundancy such that a loss of a motor will not result in "loss of
control".
In certain embodiments, a suitable conventional IMU may be used
wherein sensor data is processed in a conventional manner and not
at a virtual point on the aerial vehicle.
In certain embodiments, it is not essential to use a polling
method. Other conventional methods, implemented as programmed
algorithms, to analyze the sensor information may be used. For
example, in place of polling, outlier sensor information can be
rejected and the remaining sensor information averaged.
On a full charge, the batteries 13 provide approximately 5 kilowatt
hours of electrical energy. The lithium polymer batteries 13 must
not be run down below a threshold electrical energy level, such as
5%. If they are depleted below that level, the battery is usually
damaged. The threshold energy level can, however, be used as a one
time battery power reserve. Should the energy level of one or more
batteries fall below the threshold energy level, the remaining
energy can be used on a one-time basis to continue to provide power
to the motors 14 to enable the operator 2 to make an emergency
landing. The operating range of the individual cells of the
batteries is about 3.6 volts per cell (the minimum threshold
electrical level where the battery is considered to be "empty") to
4.2 volts (where the battery is considered to be full). All of the
batteries 13 are connected to a common bus and are thus
interconnected. This provides for balancing of any asymmetrically
loading of the motors 14 and also permits the motors 14 to draw
energy from any of the batteries 13. No single low battery will be
the limiting factor in the flight. The electrical connections
between the batteries 13 and the motors 14 are preferably minimized
to minimize resistance loses. Isolators 40 (groups of three
isolators are identified by a single reference numeral 40) are
provided to isolate certain components in the control system from
power surges and the like
Upon starting up the control system but without starting the motors
14, the voltage and temperature in each cell or set of cells of the
battery, without the load of the motors, are measured. The battery
voltages and temperatures are then used to derive the amount of
stored energy in each battery by for example using a concordance
table which relates battery voltage and temperature to stored
energy level. The initial start-up energy of the cells of the
batteries are recorded. Thereafter, for the duration of the flying
session, the power flow in and out of each battery is measured. The
power flow values are used to interpolate changes (as a result of
depletion or charging) in stored energy for each of the batteries.
The stored energy levels may be displayed to the operator in the
form of a battery power level display.
In certain embodiments, the energy content of individual battery
cells of the on-board energy storage system is measured by
measuring the voltage under a static or no load condition, along
with the temperature. A battery typically has a plurality of
battery cells. With the measured static voltage and temperature the
energy content at the measuring epoch can be calculated or
determined from a look-up table. Changes in the energy content of
the cells may be calculated by measuring the power flowing in (for
example from charging) and out (for example from applying a load
such as running the motors) of the battery cells.
In certain embodiments, the energy in each battery 13 is
continuously determined by calculating the initial battery energy
and then integrating the measured power over time. Initial battery
energy is determined by measuring both voltage and temperature of
each battery cell under substantially no-load conditions. A trivial
load such as the load to run a multi-meter may be applied to the
battery during measurement and still maintain a substantially
no-load condition. While it is not essential to measure the
temperature, measurement accuracy may be significantly affected
depending upon the temperature and the measurement tolerances
required. If the temperature is not measured, only the voltage
measurement is related to stored energy level using a table of
concordance or the like. The concordance between voltage and,
voltage and temperature, to stored energy level for a battery cell
may be determined, for example, through routine testing of a
battery cell. The battery energy monitoring may be incorporated
into the control system.
Referring to FIG. 7, in another embodiment of the present
invention, the control system is identical to that described herein
with respect to FIG. 6 except that three back-up batteries 42 are
provided instead of just one. Each back-up battery 42 is connected
to an OR gate 25.
Referring to FIG. 8, in another embodiment of the present
invention, the control system is identical to that described herein
with respect to FIG. 7 except that a back-up joystick 44 and a
back-up throttle 46 are provided with the associated wiring changes
to accommodate them. Each flight processor 27 is also connected to
back-up joystick 44 and back-up throttle stick 46 both of which are
controlled by the operator 2 of the vehicle. The back-up joystick
44 provides identical functionality to joystick 31, and back-up
throttle 46 provides identical functionality to throttle 32 are
designed to provide redundant control functionality in the event of
a failure of joystick 31 and/or throttle 32. In certain
embodiments, the joystick 44 can provide lesser functionality to
the joystick 31.
A regenerative braking/low power stability system is also provided.
In a full power out situation, the propellers will "windmill" under
control of a flight controller, allowing the vehicle to glide
rather than to lose all dynamic stability as most multi-rotor,
artificially stabilized aircraft would. The rotation of the
propellers 16 can be used to charge the batteries 13 such that, if
a sufficient charge is built up during the descent, the motors 14
may be restarted long enough to enable a controlled landing. In a
full or partial power out situation, the glide and/or orientation
of the vehicle can be controlled by controlling the rotational
speed of the "windmilling" propellers. This is accomplished by
increasing or decreasing the drag on the spinning propellers 16 by
removing varying degrees of rotational energy. In this manner,
aero-braking may be used to actively control orientation and glide
angle of the vehicle in a full or partial power-out situation. For
example, one or more motors may still be operating.
The regenerative braking system is optional. Varying the rotational
speed of the motors, operating in an electrical generator mode, can
be used to control the amount of power each motor is absorbing from
the propeller and to use that power to charge the battery system,
control the orientation and/or glide angle and/or speed of the
vehicle. In certain embodiments, energy may be removed from the
motors through resistive heating and the heat dissipated. In
certain other embodiments, energy may be removed from the motors by
using the electrical energy generated by the motor in generator
mode to charge an on-board battery. In certain other embodiments,
internal resistance of the motor may be used. For example,
electrical switching may be used to alter the internal resistance
of the motor. In certain other embodiments, mechanical breaking may
be used to control the rotational speed of the motor. In certain
embodiments, a combination of one or more of the foregoing energy
absorbing methods and systems may be used. In certain embodiments,
the control system is adapted to carry out control through
regenerative braking.
The aerial vehicle is equipped with an optional ballistic parachute
(not shown). The parachute is housed in a compartment located in
the cockpit. The parachute is designed to be deployed in an
emergency situation such as a power out situation.
In certain embodiments, the vehicle has an empty weight of
approximately 250 lbs and a useful load of approximately 450 lbs.
The gross take-off weight is approximately 700. The vehicle has a
cruising speed of approximately 55 mph and a range (with reserve)
of approximately 30 miles. The vehicle's hover power is
approximately 50% of maximum power, hover power in ground effect is
approximately 30% of maximum power and cruise power is
approximately 10% of maximum power. The vehicle is not limited to
such specifications.
As shown in FIGS. 1 and 3, when at rest, the vehicle preferably
sits on the ground with the wings inclined at approximately
45.degree. with respect to the ground. While an inclination of
approximately 45.degree. is preferred, the wings may be inclined
with respect to the ground at an angle ranging from approximately
90.degree. for fully vertical take off to approximately 0.degree.
for horizontal take-off. In alternative embodiments, the wings 3
and 4 are not parallel. The wing 3 for example may have a steeper
"angle of attack" than the wing 4 to for example stall the wing 3
before the wing 4 such as in a power out glide situation. In other
embodiments, the wing 3 may be designed with wing geometries (e.g.
size, profile and orientation) that make the wing 3 conducive to
gliding in a power out situation.
To take off, the tablet computer 29 is booted and the control
system activated. Using the throttle stick 32, the motors 14 are
turned on and the power increased to the point where the vehicle
lifts from the ground in an approximately 45.degree. degree
trajectory with respect to the ground. Power to the motors 14 is
adjusted as needed. The vehicle can continue to be flown in such a
trajectory. To vary the inclination of the trajectory, such as to
pitch the upper wing forward, the rotational speed of some or all
of the propellers 16 on the upper wing 4 is increased relative to
the propellers on the lower front wing 3 or the rotation of some or
all of the lower wing propellers is decreased relative to the upper
wing propellers or a combination thereof. This pitch control method
also applies when the vehicle is in a vertical or a near vertical
orientation, including for vertical or near vertical take off. This
pitch control method may be used to decrease the angle of attack of
the wings to transition to horizontal or near horizontal flight or
to increase the angle of attack of the wings to move to vertical or
near vertical flight. Take off can also occur in a slight reverse
direction or a sideways direction.
To land, power may be adjusted such that the vehicle descends at a
downward trajectory of approximately 45.degree. with respect to the
vertical. In other embodiments, the angle of attack of the wings
can be increased to transition the vehicle from horizontal or near
horizontal flight to a vertical or near vertical orientation and
the vehicle may then descend to the ground by reducing power to the
motors as needed.
In order to bank the vehicle in horizontal or relatively horizontal
flight, the rotational speed of some of the propellers 16 is
increased relative to the rotational speed of other propellers 16.
In an embodiment where the propellers 16 driven by motors A1, A2,
A3, A4 rotate in the same direction (such as indicated by arrows
A), and the propellers driven by motors B1, B2, B3, B4 rotate in a
counter direction (such as indicated by arrows B), the vehicle, may
be banked by increasing the rotational speed of the propellers 16
driven by motors A1, A2, A3, A4 relative to the rotational speed of
the propellers 16 driven by motors B1, B2, B3, B4. This may be
accomplished by increasing the rotational speed of the motors A1,
A2, A3, A4 and decreasing the rotational speed of the motors B1,
B2, B3, B4, increasing the rotational speed of the motors A1, A2,
A3, A4 while maintaining the rotational speed of the motors B1, B2,
B3, B4, or maintaining the rotational speed of the motors A1, A2,
A3, A4 while decreasing the rotational speed of the motors B1, B2,
B3, B4. It will be appreciated that in other embodiments, other
propeller rotation configurations can be similarly controlled.
In certain embodiments of the present invention, in order to
conduct a turn of the vehicle around the yaw axis in horizontal
flight or near horizontal flight, the rotational speed of the
propellers 16 driven by motors A1, A2, B3 and B4 is increased or
decreased relative to the propellers 16 driven by motors A3, A4, B1
and B2 in a manner analogous to that described herein with respect
to banking. In certain embodiments, superposed modulation of motors
A1, A2, A3 and A4 relative to motors B1, B2, B3 and B4 may be used
to control the bank angle of the vehicle for a turn coordinated
about the yaw and roll axes.
In certain embodiments of the present invention, the rotational
speed of the propellers 16 on one side of the vehicle can be
increased relative to the propellers on the other side to make a
decoupled yaw turn while the vehicle is in horizontal or near
horizontal flight such that the vehicle turns around the yaw axis
but does not turn substantially around the pitch or roll axis. This
is also sometimes referred to as a "skidding" turn in conventional
aviation. The turn may be controlled by increasing the rotation of
propellers driven by motors A1, A2, B3 and B4 relative to the speed
of propellers driven by motors A3, A4, B1 and B2 while conducting
superposed modulation of motors A1, A2, A3 and A4 relative to B1,
B2, B3 and B4 motors in order to stabilize the vehicle about the
roll axis. This will cause the vehicle to conduct a turn of the
vehicle about the yaw axis while the vehicle does not turn
substantially around the roll or pitch axes.
The propellers 16 are arranged in pairs in four quadrants relative
to the centre of the vehicle. If one motor 14 fails during
operation of the vehicle, power to the other motor 14 in the same
quadrant can be increased to increase the rotational speed of the
propeller 16 to compensate for the failure. For example, if motor
A1 fails, power to motor A2 can be increased to compensate for the
failure. The same compensation method may be applied to motors
arranged in other configurations provided that the configuration is
relatively symmetrical.
In the event of a failure of two motors 14 in the same quadrant
during operation, a motor 14 in the opposite quadrant is reversed
and the other motor 14 in that quadrant is modulated. For example,
if motors A3 and A4 fail, motor A1 can be reversed and motor A2
modulated or alternatively, motor A2 can be reversed and motor A1
modulated.
It should be noted that the figures merely depict certain possible
configurations of aerial vehicles that utilize the propulsion and
control systems described herein, and that fewer or more motors 14
may be used without deviating from the spirit of the invention.
Furthermore, the cockpit 1, fuselage 20 and struts are
non-essential. Fewer or more wings can be used but there must be at
least one wing or airfoil. Various wing structures and sizes can be
used including a complete ring wing structure, as can other foil
sections such as tapered and twisted. The propulsion and control
systems according the present invention may be used as appropriate
with such wings or foils. A flying wing structure can be employed
such as a complete ring wing structure.
In certain embodiments of the present invention, the vehicle does
not include a tail or rudder and can be substantially controlled by
differential thrust, that is varying the thrust of one or more of
the thrust producing elements. In certain other embodiments of the
present invention, the vehicle does not include any control
surfaces and can be substantially controlled by differential
thrust. In certain other embodiments of the present invention, the
vehicle does not include any control surfaces except for one or
more trim tabs, and can be substantially controlled by differential
thrust.
Aerial vehicles according to embodiments of the present invention
are not limited to the control systems described herein. It will be
appreciated that the control systems described herein are exemplary
of control systems that may be used to control the vehicle. It will
be appreciated that other suitable control systems, including
synthetic control systems, may be used to carry out the desired
control of aerial vehicles according to embodiments of the present
invention.
The propulsion system for vehicles according to embodiments of the
present invention are not limited to propellers. In certain
embodiments, other thrust producing elements may be used such as
turbines and ducted fans. Various combinations of different thrust
producing elements may also be used.
Aerial vehicles according to embodiments of the present invention
may be manned or unmanned. Aerial vehicles according to embodiments
of the present invention may be controlled by a human operator in
the vehicle or remotely or a combination thereof.
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